title: Identification of a Maize Kernel Pathogenesis-Related Protein and Evidence for Its Involvement in Resistance to Aspergillus flavus Infection and Aflatoxin Production.
abstract: ABSTRACT Aflatoxins are carcinogens produced by Aspergillus flavus and A. parasiticus during infection of susceptible crops such as maize. Several aflatoxin-resistant maize genotypes have been identified and kernel proteins have been suggested to play an important role in resistance. In the present study, one protein (#717), which was expressed fivefold higher in three resistant lines compared with three susceptible ones, was identified using proteomics. This protein was sequenced and identified as a pathogenesis-related protein (PR-10) based on its sequence homology. To assess the involvement of this PR-10 protein (ZmPR-10) in host resistance of maize against fungal infection and aflatoxin production, the corresponding cDNA (pr-10) was cloned. It encodes a protein of 160 amino acids with a predicted molecular mass of 16.9 kDa and an iso-electric point of 5.38. The expression of pr-10 during kernel development increased fivefold between 7 and 22 days after pollination, and was induced upon A. flavus infection in the resistant but not in the susceptible genotype. The ZmPR-10 overexpressed in Escherichia coli exhibited a ribonucleolytic and antifungal activities. Leaf extracts of transgenic tobacco plants expressing maize pr-10 also demonstrated RNase activity and inhibited the growth of A. flavus. This evidence suggests that ZmPR-10 plays a role in kernel resistance by inhibiting fungal growth of A. flavus.
authors.affiliation: First and fourth authors: Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803 ; and second, third, and fifth authors: Southern Regional Research Center, United States Department of Agriculture-Agricultural Research Service, New Orleans, LA 70179.
authors.forename: Z-Y
authors.initials: ZY
authors.lastname: Chen
authors.forename: R L
authors.initials: RL
authors.lastname: Brown
authors.forename: K
authors.initials: K
authors.lastname: Rajasekaran
authors.forename: K E
authors.initials: KE
authors.lastname: Damann
authors.forename: T E
authors.initials: TE
authors.lastname: Cleveland